<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        div {
            width: 200px;
            height: 200px;
            background-color: pink;
        }
    </style>
</head>

<body>
<div></div>
<script>
    // 1. 获取元素
    const div = document.querySelector('div');
    // 2. 注册事件 处理程序
    div.onclick = function () {
        // div.style里面的属性 采取驼峰命名法
        this.style.backgroundColor = 'purple';
        this.style.width = '250px';
    }
</script>
</body>

</html>
